Automotive vehicles are commonly equipped with a torque converter located between a vehicle engine and an automatic transmission to transmit torque. The torque converter transmits torque via fluid provided by a transmission oil pump.
A rotor for the oil pump is typically mounted on a torque converter hub. Commonly, fluid pumping losses across the pump rotor occur due to operating clearances on mating parts and manufacturing tolerances. Fluid typically leaks across the pump rotor from a high pressure cavity outside the pump rotor to a low pressure area near the torque converter hub. The low pressure area near the torque converter hub, however, is part of the apply passage for the torque converter clutch. Thus, fluid leakage across the pump rotor is increased when a torque converter clutch is in a disengaged position and the pressure differential across the pump rotor face is higher.